Genes from many isolates of the influenza virus have been sequenced.In certain regions of the genome, nonsynonymous substitutions are much more frequent than synonymous substitutions.Which statement is the most likely explanation for this pattern?

Question

Quizplus · Accepted Answer

The high frequency of nonsynonymous substitutions suggests that strong positive selection is acting on these genes. This means that certain amino acid changes provide an advantage to the virus in its ability to infect and/or replicate in its host. This selection pressure drives these beneficial changes to become fixed in the population.

Genes from Many Isolates of the Influenza Virus Have Been